Fork Faceoff!

For my first full season of mountain biking, I have decided to purchase a 29er. Due to price range, test riding, and availability my favored local bike store I have decided I am going to purchase a Cannondale Trail SL 29'er.

The question here is whether I'm going to, with my weight (280-300ish), destroy the air fork (really, an air fork in general) on the nicer model. I'd really rather have the 9-speed setup, hydraulic brakes, etc...but I'd also rather not blow my fork apart on the trail.

(If there's a primer on this, I would super appreciate a link - I've been doing a bit of googling/forum searching and have not found it.)

Only thing I've seen on that was in the past, I had downloaded Cannondale's catalog, and it has maximum rider weights in it. But they're basically the same for all of the same style of bike (likely, all the mountain bikes would have the same rating, for example.)

I assume you rode the SL-2? Hit any good bumps on it? How did it feel? How did the bike react when braking?

I'm in your weight class and you're right to be concerned about air shocks in general. I test rode a bunch of bikes that had low-budget air shocks on them and it was like riding a rocking chair. (Plus major front wheel dive when braking.) I ended up with a Kona Hoss which has an air shock on it -- no issues.

You say you test rode. I assume that means at least one of these bikes. How did the fork perform? Did you get it out into conditions similar to what and where you plan to do your riding? Did it bottom out frequently, or at all? Is it adjustable, or does it have a complete lockout setting?

FWIW, I got my Fisher when I was just under 300 lbs and while it exhibited a bit of nose dive under hard braking at that weight, the fork has really never been much of an issue, at least for the pavement riding I do with it. I've never taken it off road.

For my first full season of mountain biking, I have decided to purchase a 29er. Due to price range, test riding, and availability my favored local bike store I have decided I am going to purchase a Cannondale Trail SL 29'er.

The question here is whether I'm going to, with my weight (280-300ish), destroy the air fork (really, an air fork in general) on the nicer model. I'd really rather have the 9-speed setup, hydraulic brakes, etc...but I'd also rather not blow my fork apart on the trail.

(If there's a primer on this, I would super appreciate a link - I've been doing a bit of googling/forum searching and have not found it.)

Suspension forks in general are not made for 300lb riders, the way an air-shock works is that it uses air pressure to hold up the weight, the problem is that there are seals to hold the air pressure where it should be, and those seals have a maximum pressure rating. If you exceed that pressure, then the seals could blow, and you may find that it's not covered by warranty. The SL-2 has a Deuce Air fork, which is one RST makes for Cannondale. If you look at the fork manual you will find a table where for weight X the pressure that should be used is Y, that number tops out at 260lbs, you can probably push it a little past that, but you can't be sure by how much. Of course you could always lose 40lbs....

The question here is whether I'm going to, with my weight (280-300ish), destroy the air fork (really, an air fork in general) on the nicer model. I'd really rather have the 9-speed setup, hydraulic brakes, etc...but I'd also rather not blow my fork apart on the trail.

The forks on both bikes appear to be entry-level equipment. Heck, you could spend as much money on some Fox forks as it would cost to buy a base-model SL29er! As such, I would expect that you're outside the recommended weight range. In your situation, I would ask your LBS two questions: 1) what sort of fork problems does the bike's warranty cover and how are they addressed, and 2) how much does it cost to rebuild the fork if the seals blow after the warranty expires? I'd be especially concerned if your shop can't work on the fork in-house, or if the fork has to be sent back to the factory for warranty work.

Unfortunately, there just aren't a lot of great suspension options for Clydes. If you buy a coil-spring fork, it'll be difficult/impossible to find a spring matched to your weight. Air springs are a better bet, but many models aren't designed to handle Clyde-type weights. If I were in your shoes, my strategy would be to start saving now for a replacement fork and make sure that your LBS will stand behind the fork you're going to get with the bike. You might even negotiate this into the purchase: tell them you think you'll want to upgrade the fork within 6-12 months and ask what sort of deal they'll guarantee on that future purchase. Have them make a note about the discount ("New fork for cost+15% within 12 months of purchase") on the paperwork you get with the bike, so they don't forget.

I think that at the end of the day, I'm going to go with the SL 4 (the lower-priced model with the coil fork) - simply because everything on the bike seems pretty decent to begin with (for entry-level gear, that is) and is able to be ridden until it breaks and then upgraded if necessary.

For reference, last season I put about a thousand miles on a lowest-of-the low Suntour fork, split between street and trail riding and it's still in pretty decent shape. This fork looks to be of higher quality, so I'd imagine I'll be able to put at least that amount of punishment on there.

If it were me, I'd go with the SL2. Hydraulic brakes and a 9-speed drive-train combined with Deore shifters, Deore rear derailleur, and a Shimano crank would be a big plus for me. In addition, with an air spring fork you're probably more likely to be able to achieve the proper amount of sag, or at least get close, and thus suspension response.

If you want a coil spring fork to work well, it is imperative that you acquire and install a spring matched to your weight. This may be difficult, especially on a low-end fork. Pounding around on a under-sprung fork is a great recipe for breaking something.

Have you ridden both bikes on your local trails? Was the suspension setup so that it didn't bottom out? If so, then there's probably nothing to worry about...

The test-riding I did was on suburban streets behind the store, as that was what I was able to do at the time. HOwever, I did make sure to go up and down a few curbs to test the suspension and neither fork bottomed out.

If I can use the air fork and not demolish it, I'm all for the SL2 - the other components on there are a very nice package.

If I can use the air fork and not demolish it, I'm all for the SL2 - the other components on there are a very nice package.

I have to admit: this is usually what I do... an it's not a terribly good test. A single bump is usually pretty easy for the suspension to handle. The problem is when you have multiple bumps in quick succession. If the suspension doesn't have enough rebound, it can start to "pack" with each successive bump to the point where it is fully compressed after several bumps.

I'd ask your LBS for their guidance on whether the bike is appropriate for the riding you intend to do. Cannondale's on-line manuals seem to suggest that most of their bikes are rated for riders of up to 300lbs, so you're probably fine. Still, it wouldn't be a bad idea to budget for having the fork re-built once or twice per year. That's why I suggested asking the shop how much a rebuild would cost. The parts are usually cheap; it's a question of how much labor is involved.